Suppose one is learning chemistry at home. What type of fire extinguisher one should ideally get? It seems the dry powder option is the cheapest ($\approx 30€$), foam mid-priced ($\approx~60€$) and the one using carbon dioxide the most expensive ($\approx~150€$). I did not find solutions based on water/wet chemicals/halon yet, though I know such exist. If there's no differences in achieved safety, I would probably pick the dry powder one.

$\begingroup$Welcome to chemistry.SE! If you had any questions about the policies of our community, you can ‎visit the help center or take a tour of the website .‎ || When it comes to safety, I wouldn't think about expenses that much, especially when I'm the one conducting an experiment optionally. This is a nice question though.$\endgroup$
– M.A.R.Jan 21 '15 at 19:07

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$\begingroup$This is highly dependent on what experiments you're going to conduct. Water is the cheapest extinguisher, but at times it's not effective, chemically harmful or even could make matters worse. I think it's better if you mention what "home experiments" you're going to try.$\endgroup$
– M.A.R.Jan 21 '15 at 19:11

$\begingroup$I'm studying the equivalent of two first courses of general chemistry (uni level). The topics vary a lot but you as chemists probably know what such 1st-year university courses typically contain.$\endgroup$
– safetyJan 21 '15 at 19:18

$\begingroup$A bucket of sand would be the most useful one for small experiments, it works on most reactions, doesn't cause much damage and is very cheap. A real fire extinguisher would still be useful for any larger fires.$\endgroup$
– Mad ScientistJan 21 '15 at 20:01

2 Answers
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You need to investigate the safety and handling of every chemical you use in your experiments individually. The handling and safety precautions can be very different depending on what substances exactly you use.

In terms of fire, the one thing you must know before each experiment is which methods won't work or even fail catastrophically. Trying to extinguish a sodium fire with water is a really, really bad idea, and that is something you must know in advance.

Metal fires are the most common kind of fire where you have to be careful about choosing the right method. Some metal fires can't even be extinguished by carbon dioxide. There are special fire extinguishers for this (class D), other methods might not work.

A bucket of sand is the most useful method for small fires in a lab. It works for almost everything and doesn't cause a big mess. But it is obviously useless if you cause a bigger fire and can't reliably cover it with sand anymore.

Powder extinguishers cause quite a mess, you'll spend a lot of time cleaning up the room afterwards. Obviously this is a lot better than burning down your home, but I wouldn't use them for small fires you could stop with some sand.

Foam and powder are probably the most useful general-purpose extinguishers. Carbon dioxide is a bit trickier to use from what I heard, I probably wouldn't recommend it in your case.

Thinking about a fire extinguisher is a good first step. Another thing I very strongly recommend is that you read up on general safety procedures in the lab. Simple things like not storing large amounts of solvent directly in your fume hood (or workplace) might prevent a small fire from becoming a dangerously large one. Knowing that you need to inactivate any reactive reagents before disposing them might save you from throwing away some oxidizing agent and accidentally setting your waste on fire. There is a lot more to chemical safety than just choosing the right fire extinguisher.

$\begingroup$I would also suggest fire blanket. The carbon dioxide extinguisher is quite usable for small incidents. Quite often you just blow off the flame or fill some reasonably contained area (fume hood) with CO2. In terms of speed, blanket is fastest, costs close to nothing and you can have it just at the workplace. Also usable for extinguishing yourself.$\endgroup$
– ssavecJan 22 '15 at 13:47

Admittedly, I'm not a big fan of experimenting at home - particularly when (larger volumes of) flammable liquids are involved.

Home labs typically lack huge sinks with faucets high and huge enough to get a face under it. Neither do they have a fire shower at the exits, which is standard in German university labs. This aside and adding to the answer given by Mad Scientist:

Foam extinguishers work well even in the rare case when a person is on fire. This does however require a second person to operate it! With respect to this and other scenarios, where pain and panic prevents you from treating a mishap reasonably (acid and alkaline spills in the face, severe cuts due to breaking glas, strong burns, etc.) the golden rule for students in university labs therefore is: NEVER work alone!